Coating process



Nov. 9, 1943. w. E. BEADLE, sl-'e4 2,333,629

COATING' PROCESS Filed July 14, 1941 Patented Nov. 9, -1943 COATINGPROCESS Warren E. Beadle, Sr., Wisconsin Rapids, Wis., assignor toConsolidated Water Power and Paper Company, Wisconsin Rapids, Wis., acorporation of Wisconsin Application July 14, 1941, Serial No. 402,302

4 Claims.

This invention relates to improvements in a process of coating paper orother flexible brous webs to impart thereto a smooth, uniform surfacesuitable for the reception of fine printing, and a machine for carryingout said process.

In the coating of paper, fibrous board or the like, to impart thereto asurface which partakes of the characteristics of the coating materialrather than those of the base brous web, the

desideratum is to produce a surface which is uniform in texture, smoothand one which will not be lifted from the web during calendering orprinting orsubsequent operations.

Brieiiy described, my. invention comprises passing a fibrous webforwardly in step with the formation of the web on a paper machine, oras a separate operation apart from the paper machine; bringing a surfaceof said web into contact with a rotating surface having a peripheralspeed slower than the translatory speed of the web, the rotating surfacebeing adapted to deposit coating material upon the surface of the webwith a wiping and smoothing action; performing the same operation on theopposite side of the web, and while the coating material is still in amobile state, passing the web between two opposed rotating pressuresurfaces. Air, preferably heated, is then blown upon the coated surfacesto preliminarily set the coating and subsequently the web is passed overdrum driers to fully dry the coated surfaces.

The objects and advantages of my invention will be apparent from theaccompanying drawing and following detailed description.

In the drawing, the single figure is a diagrammatic view of suitableapparatus for carrying out my invention.

Referring in detail to the drawing, I and 2 indicate the final two drierdrums o f a battery of drier drums which constitute the dry end of theusual paper machine. ried through the dry end of the paper machine andpasses around drums I and 2. After passing from drum 2 the web 3 issubstantially dry in the sense that the term is used in the paper makingart. that is, it contains less than percent moisture. If desired, afterleaving drum 2, the web may be passed through the usual machine calender(not` shown) or the web may be passed directly from the dry end to mycoater 4.

The coating unit 4I comprises frames 5 and Ii, which when joinedtogether, as shown, form substantially an A-frame. A secondary framev 1is positioned beneath the frame E and is substantially triangular inshape, said frame carry- A web of paper 3 is carv ing diagonally spacedbearings 8 and 9 which are adapted to carry, respectively, rolls I0 andII. A

pan I2 is also carried by the secondary frame 1 immediately beneath rollIll, said pan being provided with a drain pipe I3 whereby coatingmaterial which is received by said pan may be removed.

Similarly, a secondary frame I4 is positioned beneath frame 5, saidsecondary frame I4 being offset upwardly with respect to secondaryframe 1. Secondary frame I4 carries diagonally spaced bearingsjl5 and I6which, respectively, support rolls Il and I8. A pan I9 is positioned onthe secondary frame I4 immediately beneath roll I'I,

said pan being provided with a drain pipe 2l).

Rolls l0 and Il are preferably separately and independently driven byany suitable driving means (not shown) as are rollsI'I and I8. A header2| is positioned above the nip of rolls I0 and I I and feeds a stream ofcoating material to said nip to form a pool therein. Similarly, a header22 is positioned above the nip of rolls I'I and I8 to deliver coating tothe nip of rolls i1 and I8.

The coating material employed may comprise a mineral suspensioncomprising a mineral pig"- ment such as satin white, blanc x, or any ofthe usual coating clays; an adhesive suchr as starch, caseinor the like,and a dia \ersing agent such as water soluble soaps. Of course, althoughmy invention is particularly adaptable for coating paper or board forprinting purposes ernploying a mineral suspension as the coatingmaterial, other coating materials are contemplated such as varnishes,resins, rubber latex coatings or the like, the feature of my inventionresiding in the fact that the coatings can bey applied in an extremelysmooth and uniform manner.

Web 3 after leaving drum ,2 is trained around guide rolls 23 and 24 andpassed tangentially into contact with the rotating surface of r'oll I I.Rolls I0 and II are substantially in contact with each other and arepreferably driven at different peripheral speeds. The difference inperipheral speed of the two rolls controls, to a degree, the amount ofcoating material which will be carried l on the surface of roll II, andhence, the amount of coating material which will be transferred to weblscoated. vThe relationship and function of rolls I1 and I6 is similar tothat of rolls III and Ii, as has been hereinbefore described. It will benoted that roll Il is offset with regard to roll Il whereby the 'web is-wrapped a slight degree about each of the coating rolls therebyinsuring adequate contact between the coating roll surfaces and the web.

As has been hereinbefore described, the peripheral speed of rolls Il andIl is less than the translatory speed of the web. 'I'his arrangementpermitsy a wiping and smoothing action to take place which is conduciveto a smooth and uniform resulting coated surface. Preferably, the solidscontent and viscosity of the coating material are relatively high sothat the greatest advantage of the wiping an`d smoothing action may besecured.

Ihe web 3 after leaving roll I9 is passed between rolls 25 and 26. Thecoating material upon the opposite surfaces of the web during `passageof the web between the rolls 25 and 26, is in a mobile state andpressure is exerted upon the web by said rolls whereby the coatingmaterial is compacted and forced into the pores and interstices of thepaper web.` An additional smoothing action is performed by the rolls 25and 26 although said rolls have a peripheral speed substantially equalto the translatory speed of the web. Rolls 25 and 26 may be drivenindependently or may be geared together.

Roll 25 is mounted upon shaft 21 which, in turn, is journalled inbearing 29. Bearing 28 is mounted upon the upper portion of frame 5. Aframe 29 is pivotally mounted as at 30 on frame 6. Roll 26 is carriedupon shaft 3l which, in turn, is journalled in bearing 32 carried uponframe 29. A cylinder 33 carrying a lug 34 at its lower end is pivotallyjoined as at 35 to a support 36 mounted upon the floor. A piston rod 31is slidably positioned within cylinder 33 and is pivotally connected asat 36 to frame 29. Means (not shown) is provided for introducing liquidunder pressure into the cylinder 33 to move piston rod 31 inwardly oroutwardly within the cylinder 33 to rock frame 29 about its pivotalmount 30.

A screw 39 is threadedly positioned in a portion of frame 29 and carriesa capstan head 40. A nut 4I functions to lock screw 39 at a desiredposition with respect to frame 29. When the piston rod 31 movesupwardly, frame 29 is rocked in a clockwise direction until the head 40contacts frame 6. It can readily be seen that the screw 39 therebyfunctions as a stop which determines the minimum degree of proximitybetween rolls 25 and 26. A pin 42 ismounted upon frame 6 and a pin 43 ismounted upon frame 29. A link 44 embraces both pins and functions tolimit the counterclockwise movement of frame 29 with respect to frame 6.It can readily be seen that by the provision of the pneumatic forcingmeans a headers 41 and 48 respectively. The chests 45 7 and 46 areprovided with suitable perforations whereby the web, in passing betweenthe chests is bathed in air. The air discharged into contact with thecoated surface of the web is preferably heated whereby a preliminary setis impartedto the coating carried upon the web surfaces. u

Subsequently the web 3 passes around drum 49 which isv preferably heatedand is then carried around a plurality of conventional drier drums 50and 5I to fully dry the coating. The web may then be calendex'ed orsuper-calendered and rolled or sheeted.

,It can readily be seen that herein is a process for forming a uniformand smooth surface of coating material upon the surfaces of acontinuously passing web, the process being characterized by the factthat the coating material is applied by rotating surfaces which rotatein contact with the web surfaces and have peripheral speeds which areless than the translatory speed of the web. To compact and force thecoating material into thepores and interstices of the fibresconstituting the web, pressure is applied to the opposite surfaces ofthe web. Simplicity and speed, together with smooth and uniform coatedsurfaces feature my invention.

I claim as my invention:

1. A method of coating a continuously advancing relatively flexiblefibrous web which comprises, depositing a controlled amount of mobilecoating material upon a rotating surface, rotating said surface incontact with an unsupported surface of said web and in the samedirection of movement with said web and at a speed less than thetranslatory speed of said web to apply a coating to said web surfacewith a wiping action, and subsequently passing said web between opposedpressure surfaces while the coating material upon the web is in a mobilestate to only thereafter compact said coating material upon said websurface, and drying said coated surface.

2. A method of coating a continuously advancing relatively flexiblefibrous web in substantially dry condition'which comprises, depositing acontrolled amount of mobile coating material upon a rotating surface,rotating said surface in contact with an unsupported surface of said weband in the same direction of movement with said web. and at a speed lessthan the translatory speed of said web to apply a coating to said websurface with a wiping action While causing the web to be wrapped aslight degree about said rotating surface, and subsequently passing saidweb between opposed pressure surfaces while the coating material uponthe web is in a mobile state to only thereafter compact said coatingmaterial upon said web surface, and drying said coated surface. Y

3. A method of coating a continuously advancing relatively flexiblefibrous web which comprises, depositing a controlled amount of mobilecoating material upon a rotating surface, rotating said surface incontact with a surface of said web and in the same direction of movementwith said web and at a speed less than the trans1a tory speed of saidweb to apply a coating to said web surface with a wiping action,depositing a controlled amount of mobile coating material upon a secondrotating surface, rotating said second rotating surfacein contact withthe opposite surface of said web at a speed less than the translatoryspeed of said web to apply a coating to said web with a wiping actionafter the first coating has beenapplied, and subsequently passing saidweb between opposed pressure surfaces while the coating material uponthe web is in a mobile state to only thereafter compact said coatingmaterial upon said web surfaces, and drying said coated surfaces.

asssae 3 4. A method of coating a continuously advancing relativelyflexible substantially dry fibrous web which comprises, passing said webupwardly in a substantially vertical direction, depositing a controlledamount oi mobile mineral coating material upon a rotating surface,rotating said surface in contact with a surface of said web and in thesame direction of movement with said web and at a speed relatively less-than the translatory speed of said web to apply a coating to said websurface with a wiping action, and subsequently passing said websubstantially vertically upwardly between opposed pressure surfaceswhile the coating material upon the web is in a mobile state to onlythereafter compact said coating material upon said web surface, anddrying said coated surface.

y WARREN E. BEADLE, SR.

